English verb conjugation
COULD TAX

Regular verb: tax - taxed - taxed

Affirmation

Simple form	V-ing form
I could tax you could tax he could tax we could tax you could tax they could tax	I could be taxing you could be taxing he could be taxing we could be taxing you could be taxing they could be taxing
Perfect	V-ing perfect
I could have taxed you could have taxed he could have taxed we could have taxed you could have taxed they could have taxed	I could have been taxing you could have been taxing he could have been taxing we could have been taxing you could have been taxing they could have been taxing

Negation

Simple form	V-ing form
I couldn't tax you couldn't tax he couldn't tax we couldn't tax you couldn't tax they couldn't tax	I couldn't be taxing you couldn't be taxing he couldn't be taxing we couldn't be taxing you couldn't be taxing they couldn't be taxing
Perfect	V-ing perfect
I couldn't have taxed you couldn't have taxed he couldn't have taxed we couldn't have taxed you couldn't have taxed they couldn't have taxed	I couldn't have been taxing you couldn't have been taxing he couldn't have been taxing we couldn't have been taxing you couldn't have been taxing they couldn't have been taxing

Interrogative form

Simple form	V-ing form
could I tax? could you tax? could he tax? could we tax? could you tax? could they tax?	could I be taxing? could you be taxing? could he be taxing? could we be taxing? could you be taxing? could they be taxing?
Perfect	V-ing perfect
could I have taxed? could you have taxed? could he have taxed? could we have taxed? could you have taxed? could they have taxed?	could I have been taxing? could you have been taxing? could he have been taxing? could we have been taxing? could you have been taxing? could they have been taxing?

Interro-negative form

Simple form	V-ing form
couldn't I tax? couldn't you tax? couldn't he tax? couldn't we tax? couldn't you tax? couldn't they tax?	couldn't I be taxing? couldn't you be taxing? couldn't he be taxing? couldn't we be taxing? couldn't you be taxing? couldn't they be taxing?
Perfect	V-ing perfect
couldn't I have taxed? couldn't you have taxed? couldn't he have taxed? couldn't we have taxed? couldn't you have taxed? couldn't they have taxed?	couldn't I have been taxing? couldn't you have been taxing? couldn't he have been taxing? couldn't we have been taxing? couldn't you have been taxing? couldn't they have been taxing?