In February, the Government launched a consultation into possibilities for an online sales tax to ease the business rates burden on high street stores.
In it he wrote: “Introducing an additional tax on retail, already overburdened, will simply mean retailers cut their cloth accordingly.
“This rationalisation will always start with the least profitable parts of a business, which, in the case of multi-channel retailers, will more often than not be high street stores.
"Therefore it is likely that, far from helping the High Street an online sales tax will damage shops and our high streets further, particularly in areas that require new investment to bring them back to life."
The Treasury has reportedly not yet decided if it will introduce the tax.
Mr Sunak promised the consultation at the Budget in October following businesses’ concerns of a potential tax imbalance between in-store retailers and those online.
Big name high-street shops had called for an online sales tax because they saw it as unfair that the bills for online-only retailers are far lower.
Business rates are paid on all commercial properties and are calculated based on the property value and the rent paid.